(1) Field of the Invention
This invention relates to medium set mixing grade asphalt emulsions and rapid set emulsions. More particularly, it relates to novel amphoteric emulsifiers for solventless and solvent containing mixing grade, oil-in-water anionic and cationic bituminous emulsions, which emulsifiers are the reaction products of polyamines with certain polycarboxylic acids.
(2) Description of the Prior Art
In having operations, three main practices are employed to achieve thorough mixing of bitumen and aggregate:
(1) mixing of the free flowing heated asphalt (asphalt cement) with pre-dried aggregate;
(2) mixing pre-dried aggregate with asphalt diluted with a hydrocarbon solvent (cutback asphalt, cutter stock) at ambient temperatures; and
(3) mixing aggregate with asphalt emulsions, e.g., oil-in-water emulsions, obtained by vigorous agitation of asphalt and water in the presence of an emulsifying agent.
Because of increasing cost of energy and hydrocarbon solvents and because of environmental concerns, the use of emulsified asphalt is increasing. Dependent on the emulsifier used to achieve an emulsion, anionic or cationic emulsions are obtained. In anionic emulsions, asphalt droplets are negatively charged; in cationic emulsions, the asphalt droplets bear positive charges and migrate to the cathode when an electric field is applied.
Generally, depending on the characteristics of the type of mixing and rate of break, bituminous emulsions are classified as rapid setting, medium setting and slow setting. In the case of rapid setting emulsions, mainly used for repair work of old wearing courses, the emulsion is applied on the existing surface and aggregate is spread on top, and after compaction, the road can be opened to traffic shortly after the application of the new coat (chip seal, etc.). Medium setting emulsions are mixed with aggregate prior to being used in road construction, and slow set emulsions can be mixed with aggregate and stored for a longer period of time without breaking on the aggregate surface.
Anionic bituminous emulsions are taught by Wright and Mertens in U.S. Pat. No. 3,062,829 to be prepared by employing alkali emulsifier and polyamide additives which are the condensation products of dilinoleic acid and polyalkylene polyamines. Lignin amines are taught as anionic emulsifiers in U.S. Pat. No. 3,123,569 to Borgfeldt. Also, Moorer, in U.S. Pat. No. 3,956,002, teaches an anionic emulsifier consisting of an oxygenated alkali lignin, an ethylene oxide adduct of phenol, and up to 10% by weight of sodium borate; and, in U.S. Pat. No. 4,088,505, he teaches an anionic emulsifier consisting of an alkali metal salt of an alkali lignin, an ethylene oxide adduct of phenol and water. In addition, Montgomery and Pitchford teach the alkali metal salts of complex polynuclear aromatic polycarboxylic acids as anionic asphalt emulsifiers in U.S. Pat. No. 3,344,082. Heinz, in U.S. Pat. No. 3,006,860, similarly employs alkali metal soaps of higher fatty acids as those found in tall oil.
Cationic emulsions are obtained by employing a variety of nitrogen containing organic compounds, such as fatty amines, fatty diamines, fatty triamines, fatty amidoamines, fatty imidazolines, fatty mono- and diquaternary ammonium salts, and reaction products of all these compounds with ethylene oxide. The fatty radical of these compounds can have a variety of chemical structures, and the building blocks for the preparation of these amines can be obtained from a variety of sources, such as petroleum refinates, animal fats, vegetable and fish oils, and tall oil. Amidoamines suitable as emulsifiers are disclosed in U.S. Pat. No. 3,230,104 to Falkenberg and in U.S. Pat. No. 3,097,174 to Mertens. Combinations of fatty monoamines and triamines are disclosed in U.S. Pat. No. 3,738,852 to Doi; fatty diamines are disclosed in U.S. Pat. No. 3,728,278 to Tramelli and U.S. Pat. No. 3,518,101 to Gzemski; fatty quaternary and diquaternary salts and modifications thereof are disclosed in U.S. Pat. No. 3,220,953 to Borgfelt, U.S. Pat. No. 3,867,162 to Elste, U.S. Pat. No. 3,764,359 to Dybalski, U.S. Pat. No. 3,957,524 to Doughty and U.S. Pat. No. 3,466,247 to Ohtsuka, and fatty imidazolines are taught in U.S. Pat. No. 3,445,258 to Ferm.
The most common surface active amphoterics are obtained by reacting tertiary fatty amines with chloro-aliphatic acids, chloroalkylsulfonic acids or cyclic lactones or sultones of the same. These compounds are referred to as betaines or Sulfobetaines.RTM.. Compatible with all other classes of surface-active agents, these compounds have uses in cosmetic soap bars, liquid hand soap, soap-based shampoos, germicidal soap preparations, and soap-based laundry preparations.
Generally, asphalt emulsions prepared with fatty amines, fatty diamines, fatty amidoamines, etc., are unstable when mixed with a variety of siliceous or calcareous aggregates. Rapid breaking on the aggregate surface is observed with an increase in stiffening. At this point, the mix becomes unworkable. To overcome this problem, it is common practice to use cutback asphalt instead of asphalt cement for medium set mixing grade asphalt emulsions. Although cutback emulsions prepared with these emulsifiers also break when mixed with the aggregate, the solvent (a hydrocarbon oil, such as naphtha, kerosene, diesel oil, etc.) decreases the viscosity of the asphalt and increases the workability of the aggregate-asphalt mix. After placement of the mixes, the solvent evaporates and the final stiff aggregate-asphalt matrix is obtained. Because of the dramatically increased cost of solvents in recent years and because of the effort to reduce pollution, suitable emulsifiers are sought for mixing grade emulsions without using solvent. The use of tallow quaternary ammonium salts and tallow diquaternary diammonium salts for making emulsions suitable for slurry seal, a solventless application, is described in U.S. Pat. No. 3,764,359 to Dybalski, and the use of a quaternary amine obtained by reacting epichlorohydrin, trimethylamine and nonylphenol for solventless mixes is disclosed in U.S. Pat. No. 3,957,524 to Doughty.
The general object of this invention is to provide versatile emulsifiers for solventless and solvent containing rapid setting and medium setting mixing grade, oil-in-water bituminous emulsions. Another object of this invention is to provide emulsifier formulations for mixing grade emulsions which give a variety of set times as expressed in percent initial washoff coating (the percent coat on the aggregate surface after one minute mixing and immediate immersion in water) and percent one hour washoff coating. A further object of this invention is to provide new amphoteric amidoamino-carboxylic acids, prepared as the reaction product of polycarboxylic acids and polyamines, suitable as emulsifiers for both anionic and cationic oil-in-water emulsions.